Food stored in domestic or commercial refrigerators or freezers tends to deteriorate as a result of the oxygen content of the atmosphere. Moreover, there is a tendency for moisture to build up in a freezer leading to undesirable deposits of ice and inefficient operation of the freezer. Excessive moisture is also undesirable in refrigerators.
UK patent specification No. 1 525 710 relates to the use of carbon dioxide supplied from a cylinder to limit the build up of ice in a refrigerated open-topped freezer cabinet. The carbon dioxide is introduced into the freezer cabinet at a region adjacent a heat-exchange surface so as to form a pocket of carbon dioxide in the aforesaid region and blanket that region from atmospheric moisture. Such a method suffers from the disadvantage that it requires the cylinder to be replaced at regular intervals. Moreover, the mere blanketing of a region of the cabinet does not prevent or hinder the ingress of water vapour through the open-top of the freezer cabinet. In order to achieve this end, it would be necessary to have a net flow of carbon dioxide out of the top of the cabinet which would be undesirable. Furthermore, there is no suggestion in UK Pat. No. 1 525 710 that there is any need to reduce the water vapour and oxygen content of the atmosphere inside a closed refrigerator or freezer cabinet.